Chlamydia infection status, genotype, and age-related macular degeneration

To evaluate whether Chlamydia (C.) infections are associated with age-related macular degeneration (AMD) and to assess if this association is influenced by the complement factor H (CFH) Y402H or the high temperature requirement A serine peptidase 1 (HTRA1) rs11200638 risk genotypes.

One hundred ninety-nine AMD patients with early and late forms of the disease and 100 unaffected controls, at least 50 years old were included in the study. Patients in the AMD and control groups were selected based on known CFH Y402H variant genotype status (one third homozygous CC, one third heterozygous CT, and one third wild-type TT). Plasma from all patients and controls was tested for C. pneumoniae, C. trachomatis, and C. psittaci IgG seropositivity using a micro-immunofluorescent assay to establish previous infection status. Assays were conducted blind to risk genotypes and the results analyzed using univariate and multivariate (logistic regression) analysis.

IgG seropositivity to C. pneumoniae was most prevalent (69.2%, n=207), followed by C. trachomatis (7.4%, n=22) and C. psittaci (3.3%, n=10). No association was found between each of the three Chlamydia species IgG seropositivity and AMD status or severity (early/late). There was also no significant association between Chlamydia species IgG seropositivity and AMD status or severity, in patients carrying at least one CFH Y402H risk allele (C) or HTRA1 rs11200638 risk allele (A), with univariate or logistic regression analysis.

Chlamydia infection status does not appear to be associated with AMD status or severity. The presence of CFH Y402H and HTRA1 rs11200638 risk genotypes does not alter this negative association.